The activity of stem cell processes is regulated by internal and external signals of the cell “niche”. In general, the niche of stem cells can be represented as the microenvironment of the cells, providing a signal complex, determining the properties of the cells. At the same time, the “niche” concept implies feedback. Cells can modify their microenvironment, supporting homeostasis or remodeling the composition and structure of the extracellular matrix. To ensure the regenerative potential of tissue engineering products the “niche” concept should be taken into account. To investigate interactions in an experimental niche, an original hydrogel biopolymer scaffold with encapsulated mesenchymal adipose-derived stem cells (ASCs) was used in this study. The scaffold provides for cell adhesion, active cell growth, and proliferative activity. Cells cultured within a scaffold are distinguished by the presence of a developed cytoskeleton and they form a cellular network. ASCs cultured within a scaffold change their microenvironment by secreting VEGF-A and remodeling the scaffold structure. Scaffold biodegradation processes were evaluated after previous culturing of the ASCs in the scaffolds for periods of either 24 h or six days. The revealed differences confirmed that changes had occurred in the properties of scaffolds remodeled by cells during cultivation. The mechanisms of the identified changes and the possibility of considering the presented scaffold as an appropriate artificial niche for ASCs are discussed.

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Цель: разработать модель биомедицинского клеточного продукта, согласующуюся со стратегией «гомологичный препарат» на основе протоколов подготовки клеточной составляющей и скаффолда-носителя для доклинических исследований на крупном лабораторном животном (свинье). Материалы и методы. Биомедицинские клеточные продукты-эквиваленты кожи (ЭК) формировали с использованием криопреципитата плазмы крови здоровых доноров и мезенхимальных стволовых клеток (MSCs) жировой ткани человека. Для формирования модельных эквивалентов кожи (мЭК) использовали криопреципитат плазмы крови свиней и MSCs жировой ткани свиней. Наблюдение за состоянием клеток в культуре и в составе эквивалентов проводили с использованием методов светлого поля, фазового контраста (Leica DMI 3000B) и флуоресцентной микроскопии (имиджер Cytation 5; BioTek, USA). Скаффолды эквивалентов тестировали на цитотоксичность (МТТ-тест, метод прямого контакта). Характеристику плотности распределения клеток проводили авторским способом (Пат. № 2675376 РФ). Результаты. Разработан модельный эквивалент кожи (мЭК) для проведения доклинических исследований на крупном лабораторном животном (свинье). В мЭК замещены компоненты, переходящие из алогенных условий в ксеногенные при трансплантации животному. Представлен комплексный подход для подготовки мЭК, включающий забор первичного биоматериала свиньи, выделение и характеристику MSCs жировой ткани, подготовку скаффолда-носителя, соответствующего стратегии «гомологичный препарат». Проведена оценка цитотоксичности скаффолда мЭК. Показано, что мЭК обеспечивает аналогичную эквиваленту кожи (ЭК) механическую поддержку клеток и сопоставимое развитие клеточных событий при культивировании. Вывод. Разработана модель биомедицинского клеточного продукта, согласующаяся со стратегией «гомологичный препарат» для доклинических исследований на крупном лабораторном животном (свинье). Представлен комплексный подход, для разработки модельного эквивалента основанный на протоколах подготовки и тестирования клеточной составляющей, скаффолда-носителя и готового модельного эквивалента.

Introduction. One of the main factors involved in the pathogenesis of burn disease consists in the disturbance of microcirculation and haemostasis, caused by increased platelet aggregation. Mechanisms underlying the enhancement of platelet aggregation are poorly understood. Main results were obtained for adult patients at the onset of the burn disease, with no similar data on paediatric patients being available. There is evidence of a relationship between the size of platelets (MPV) and their functionality.Aim. To undertake a study of spontaneous and ADP-induced platelet aggregation and their size in children with burn disease.Materials and methods. We studied the aggregation and size of platelets in children aged 3–17 years, in whom burn areas covered 10–70 % of the body surface at the onset of the disease and before discharge. Spontaneous platelet aggregation was analysed under conditions of induced shear flow, whereas ADP-induced aggregation was studied employing a turbidimetric method. The study of platelet sizes was carried out using a conductometric method.Results. Spontaneous platelet aggregation increases significantly in children with burn disease. The integrated optical density of the formed aggregates, their area and perimeter were estimated for the first time. These indicators remained elevated even after burn wounds had been completely closed. In burn disease, changes in ADP-induced platelet aggregation were multidirectional in nature. Mean platelet volume (MPV) was increased during the acute period of burn disease, decreased during the period of toxaemia, and normalised by the time of patients’ discharge. Changes in MPV did not affect the aggregation properties of platelets. There was no correlation between the degree of aggregation and the severity of hyperfibrinogenemia. The blood of burn patients contained a large number of activated platelets, which was the reason for the increase in their spontaneous aggregation, not requiring the participation of exogenous inducers.Conclusion. An increase in spontaneous platelet aggregation was observed in children after a thermal injury, which remained elevated until the burn wounds were completely closed. A significant increase in the number of activated platelets constituted the reason for the increase in spontaneous platelet aggregation.Conflict of interest: the authors declare no confl ict of interest.Financial disclosure: the study had no sponsorship.

Purpose: The aim of our research was to study the level of erythrocyte aggregation in blood of children with inflammatory bowel disease (IBD). Materials and methods: The study included 37 patients of both sexes ages 6 to 17 with IBD (17 with CD and 20 with UC). Blood was drawn after the hospitalization of patients and at the end of the treatment before their discharge. Erythrocyte aggregation was studied using a rheoscope constructed using the method of H. Schmid-Schönbein et al. at modification of G.Y. Levin et al. The process of aggregation was recorded during hydrodynamic mixing and upon its stop. The process of erythrocyte disaggregation was recorded when creating sheer stress set at the exact rate. The morphology of aggregates in autologous plasma was studied using a light microscope. The state of erythrocyte cytoskeleton was studied by the method of thermo induction. The state of erythrocyte membranes was determined by photometry on the laser aggregometer. Results: It was established that a significant increase in the degree and rate of aggregation of erythrocytes is observed at IBD. In the course of treatment aggregation of erythrocytes is normalized in children with UC, but remains elevated at CD. The aggregation character changes at IBD-pathological structures of aggregates appear along with the rouleaux. A correlation between ESR, fibrinogen concentration and the degree of erythrocyte aggregation was found. It was established that hyperaggregation of erythrocytes in IBD was caused by changes not only in plasma factors, but also in the cytoskeleton and in the erythrocyte membrane. Conclusion: Thus, disorders of the rheological properties of blood are an important factor in the pathogenesis of IBD in children causing ischemic damage to the intestine. This gives grounds for recommending the use of additional methods for combating hypoxia and microcirculatory disturbances during IBD.